This invention relates to an electronic device, such as an electronic still video camera, which, on the basis of a physical signal (such as an electric signal, magnetic signal or optical signal ), is capable of being coupled to a memory cartridge when the cartridge is loaded in the device at a predetermined location thereof. The electronic still video camera mentioned here refers to a camera which stores a video signal representing a still picture in a memory device in the form of digital data.
Attempts have been made to develop IC cards, CPU cards and memory cards, which incorporate an internal semiconductor element such as an IC or a semiconductor device, for use in a wide variety of fields as a substitute for conventional magnetic cards, a substitute for external memories such as floppy discs, and as novel electronic media or control means. Some of these cards have been put into practical use. When such a card is loaded in a prescribed location of an automatic machine, control device or other electronic device, the device and the card are rendered connectable by a physical signal, such as an electric signal, magnetic signal or optical signal. More specifically, connection terminals on the card can be connected to a connector on the side of the electronic device, or coupling can be achieved magnetically or optically. Under these conditions, the electronic device and the card can communicate with each other and the electronic device can execute card processing, such as writing data in the memory of the card.
In general, an IC card, a CPU card and a memory card are physically handled and, as a result, the connection terminals tend to pick up grease, dust and other foreign matter, which can lead to a poor connection. When the connection terminals do not make good contact with the connector of the electronic device, the aforementioned card processing cannot take place normally. In other words, a faulty connection can cause errors to appear in the communications between the electronic device and the card and can make it impossible to write data into the memory of card correctly.
One conceivable application of a memory card having a comparatively large-capacity memory is as a medium for storing image data picked up by a digital electronic still video camera. Since a camera of this kind can be used outdoors as well as indoors, the connection terminals of the memory card easily pick up moisture and therefore tend to oxidize and corrode. This is a cause of faulty connections, which can make correct recording of video data impossible. A memory card provided with a very large memory capacity will predictably have a large number of connection terminals. Since reliable recording cannot be expected even if only one of these terminals develops a faulty connection, there is greater risk of recording failure.
The adherence of dust or other contaminants can lead to a faulty connection not only in instances where coupling depends upon the electrical contact between the connection terminals of the card and the connector of the electronic device but also in cases where coupling is achieved magnetically or optically.
Correct card processing also cannot be expected if the loading (as by insertion) of the card into the electronic device is not performed in the proper manner.
The special circumstances concerning an electronic still video camera will now be described in detail.
An electronic still video camera described in the specification of Japanese Patent Application Laid-Open (KOKAI) No. 59-183592 includes a camera body having an imaging optical system and a solid-state image pick-up device and is connected to a loadable/unloadable memory which stores, in the form of a digital signal, a video signal representing a still picture imaged by the image pick-up device. The memory storing the video signal is removed from the camera and loaded in a playback apparatus. The playback apparatus reads the video signal out of the memory and reproduces the video signal as a visible picture on the screen of a video monitor.
When photography is performed using an electronic still video camera of this type, it is necessary to load the memory in the camera accurately in order to connect the memory to the camera circuit-wise, after which photography is performed to produce a video signal which is then stored in the memory. However, since the electrical circuit-wise connection of the memory cannot be detected in this conventional electronic still video camera, it is impossible for the operator to know at the time that the memory is loaded whether the memory has actually been connected to the camera in terms of the electrical circuitry. If the connection has not been made, therefore, a video signal will not be stored in the memory even if the photographer takes a picture of a subject. This means that the photographer will have wasted his time since the picture which should have been taken will not be recorded.
Furthermore, in spite of the fact that the video signal is not being stored in the memory, the electronic still video camera will nevertheless image the subject being shot, convert the resulting video signal into a digital signal, create color separation information, optical distortion information and various types of data necessary for playback on a playback apparatus, and deliver these signals and data to connection means. Power is thus consumed wastefully.